Surface Chemical Structure of Sío2-TiO2 Sol-Gel Powders

1994 ◽  
Vol 346 ◽  
Author(s):  
G.M. Ingo ◽  
G. Padeletti ◽  
S. Dire' ◽  
F. Babonneau
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Structure ◽  
Silicon Oxide ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Oxide Surface ◽  
Surface Chemical ◽  
Titanium Tetraisopropoxide ◽  
X Ray ◽  
Increasing Temperature

ABSTRACTAmorphous SiO2, TiO2 and x SiO2-(1-x) TiO2 powders, with nominal values of x=0.9, 0.7 and 0.5, have been prepared via sol-gel, using silicon tetrahoxysilane (TEOS) and titanium tetraisopropoxide Ti(OPri)4. X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) are used for studying the surface chemical structure of the powders as a function of the air thermal treatment temperature up to 1273 K. For the whole range of temperature, XPS and XAES signals indicate that silicon and titanium are present as Si4+ and Ti4+ oxides. From the line shape of the O 1s peak, it is possible to distinguish between the single O-Ti and O-Si bonds and to disclose also the presence of Si-O-Ti cross linking bonds that are supposed to act as bridges between SiO2 and TiO2 moieties. Starting from 873 K, the Si-O-Ti bonds are broken and formation of a low amount of new Ti-O and a higher amount of Si-O bonds takes place. Si/Ti atomic ratios obtained by curve fitting the O Is peaks and from Ti 2p3/2 and Si 2p peaks, confirm the silicon oxide surface enrichment. Furthermore, with increasing temperature, XAES data indicate the formation of crystalline phases.

Composition and Chemical Structure of Nitrided Silica Gel

1984 ◽  
Vol 32 ◽  
Author(s):  
R. K. Brow ◽  
C. G. Pantano
Keyword(s):  
Thin Films ◽  
Infrared Spectroscopy ◽  
Low Temperature ◽  
Silica Gel ◽  
Photoelectron Spectroscopy ◽  
Chemical Structure ◽  
Sol Gel ◽  
X Ray ◽  
Higher Temperature ◽  
Low Temperature Treatments

ABSTRACTSol/gel derived silica thin films were thermally treated in NH3 for four hours at temperatures up to 1300C. The films were analyzed by ellipsometry, X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). Over 30 mol% nitrogen was incorporated in the film treated at 1300C. Using IR and XPS analyses, -NHx groups were found to be present after low temperature treatments, while nitrogen was incorporated in an oxynitride structure after the higher temperature treatments.

scholarly journals Heat Treatment Effect on the Phase Composition of the Silica Electrochemical Coating and the Carbon Fiber Strength

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5209
Author(s):  
Sergei Galyshev ◽  
Evgeniya Postnova ◽  
Olga Shakhlevich ◽  
Dmitrii Agarkov ◽  
Ekaterina Agarkova ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Carbon Fiber ◽  
Amorphous Silicon ◽  
Photoelectron Spectroscopy ◽  
Silicon Oxide ◽  
Fiber Strength ◽  
Sol Gel ◽  
Initial State ◽  
X Ray

This work is devoted to the study of the chemical and phase composition of a carbon fiber coating obtained by the electrochemical sol-gel method. The experimental data obtained using several independent complementary methods, including X-ray phase analysis, thermogravimetric and differential thermal analysis, scanning electron microscopy and elemental analysis, and X-ray photoelectron spectroscopy, are in good agreement with each other. It was found that the resulting coating consists of amorphous silicon oxide and crystalline potassium carbonate. Heating above 870 °C leads to the crystallization of cristobalite from amorphous silicon dioxide. At a temperature of about 870 °C, the coating acquires a smooth surface, and heating above 1170 °C leads to its destruction. Thus, the optimum temperature for the heat treatment of the coating is about 870 °C. The loss of strength of carbon fiber at each stage of coating was estimated. A full coating cycle, including thermal cleaning from the sizing, coating, and heat treatment, results in a loss of fiber strength by only 11% compared to the initial state.

scholarly journals Surface Morphological and Chemical Features of Anticorrosion ZrO2–TiO2 Coatings: Impact of Zirconium Precursor

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 703
Author(s):  
Irina Stambolova ◽  
Daniela Stoyanova ◽  
Maria Shipochka ◽  
Nelly Boshkova ◽  
Alexander Eliyas ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Composite Films ◽  
Corrosion Damage ◽  
Amorphous Structure ◽  
Treatment Temperature ◽  
Chloride Ions ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Complex Structural

Dense, highly textured, hydrophobic ZrO2-TiO2 (1:1) coatings with amorphous structure were prepared using the sol-gel method. Both organic and inorganic zirconium precursor salts were used. The present study dealt with the investigation of their protective ability in a selected model corrosive medium with chloride ions as corrosion activators. The coatings showed good anticorrosion performance during the test, which was demonstrated both by the weight loss method and potentiodynamic polarization curves. The samples were characterized by means of X-ray diffraction (XRD), Atomic Force Microscopy (AFM), contact angle measurements, Infrared spectroscopy (IRS), Scanning Electron Microscopy (SEM), Differential Thermal analysis (DTA-TG) and X-ray photoelectron spectroscopy (XPS). It was established that the extent of influence of some factors, like treatment temperature (Ttr) and type of zirconium precursor, was different. The PD curves of samples treated at 400 °C (A4 and B4, respectively) demonstrated an increased effect of the precursor in comparison to Ttr, since the application of organic Zr salt led to deterioration of the anodic passivation zones. Contrary to this, the coatings obtained from both the organic and inorganic Zr precursor salts with Ttr = 500 °C had similar corrosion efficiency, i.e., the influence of the precursor was minimized. All investigated coatings had no visible corrosion damage. It seems that some complex structural and surface parameters, such as amorphous dense structure, surface smoothness, hydrophobicity and the surface chemical composition (low hydroxyl groups content), were responsible for the increased anticorrosion properties of the composite films.

Silicon and silicon oxide surface modification using thiamine-catalyzed benzoin condensations

2012 ◽  
Vol 90 (3) ◽  
pp. 262-270 ◽  
Author(s):  
Kelly A. Hoop ◽  
David C. Kennedy ◽  
Trevor Mishki ◽  
Gregory P. Lopinski ◽  
John Paul Pezacki
Keyword(s):  
Surface Modification ◽  
Ir Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Silicon Oxide ◽  
Oxide Surfaces ◽  
Oxide Surface ◽  
X Ray ◽  
Benzoin Condensation ◽  
Aldehyde Groups ◽  
Full Conversion

The benzoin condensation that involves the umpolung coupling of two aldehyde groups has been applied to the formation of functionalized silicon and silicon oxide surfaces using thiamine and other N-heterocyclic carbene (NHC) catalysis in water. This bioorthogonal conjugation of an aldehyde to a modified silicon or silicon oxide surface has been monitored and characterized using X-ray photoelectron spectroscopy and IR spectroscopy. NHC catalysis was found to be efficient in water mediating full conversion of the aldehyde functionalized silicon oxide surfaces at the interface.

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